The present invention relates to ball for ball games such as a soccer ball, a handball, a volleyball and the like.
Conventionally, there have been two kinds of balls for ball games having an air charging structure, for example, a laminated ball and a hand stitched ball.
As disclosed in the specification of U.S. Pat. No. 4,333,648, for example, the laminated ball comprises a rubber bladder made of air impermeable rubber and having a spherical hollow body into which compressed air is charged through a valve, a reinforced layer formed by winding a fiber such as a nylon filament having several thousands meters onto the bladder in every circumferential direction in order to stabilize the quality of the ball (weight, size, sphericity, durability, shape maintenance, and an enhancement in strength for a change with the passage of time), a cover rubber layer made of a thin vulcanized rubber layer bonded onto the reinforced layer, and an outermost layer including a plurality of leather panels bonded onto the cover rubber layer. The cover rubber layer has the function of tightly bonding the leather panel onto the ball. An artificial leather panel or a natural leather panel is used for the leather panel. In many cases, an end of the back of the leather panel is usually cut obliquely (which is referred to as diagonally cutting), and a trench having an almost V shape is formed on a leather panel joint.
Since the ball having such a structure can be mechanically manufactured, it has good productivity (a small variation in weight and size) and is generally inexpensive. In addition, such a ball is excellent in sphericity and durability. On the other hand, the trench formed on the panel joint has a great width (usually about 8 mm) and has a shallow depth (usually about 1 mm). Therefore, there is a problem in that an air resistance cannot be reduced and a flight cannot be increased. There is a further problem in that the ball has poor gripping properties and is hard to grip.
The hand stitched ball has a structure in which the same bladder as described above is housed in an outermost layer having a spherical shape which is formed by folding edges of a plurality of leather panels toward the inside and sewing them together with a thread (usually about 10000 deniers). The same artificial leather or natural leather is used for the leather panel. A backing member formed by sticking a plurality of woven fabrics is usually bonded onto the back of the leather panel. More specifically, the woven fabrics are bonded onto the back of the leather panel with an adhesive such as a latex paste, thereby reinforcing the leather panel. The hand stitched ball having such a structure has been disclosed in Japanese Unexamined Patent Publication No. 19516/1997, for example.
According to the ball having such a structure, the leather panel is folded toward the inside together with the backing member. Therefore, a trench to be formed in this portion has a smaller width of about 2.5 mm and a greater depth of about 2.0 mm than in the laminated ball. Therefore, the ball has advantages that an air resistance can be reduced, a flight can be increased, and excellent gripping properties, that is, easiness to grip by hands, good operability and excellent ball controllability can be obtained. However, since the ball is a solid, it cannot be stitched by a machine but should be stitched by hands. For this reason, there is a problem in that a lot of skill is required, an individual variation is increased and productivity is poor. In addition, the quality is also uneven, and variations in weight, size and sphericity are easily generated.
When an internal pressure of about 1.0 kg/cm2 and shock such as kick are applied to the ball, force or shock of several hundreds kilograms, or more is applied. For this reason, there is a drawback that seam opening is caused. Consequently, the size of the ball is increased more than the standard or is deformed in some cases. In the worst case, there is a danger that the thread might be broken or be unknotted due to the shock to cause the bladder to project. The durability of the hand stitched ball is usually about xc2xd to ⅓ of that of the laminated ball.
It is an object of the present invention to improve aerodynamic characteristics and the like of the structure of the laminated ball. The present invention solves the above-mentioned problems by forming the same trench as in the hand stitched ball on the joint of the leather panel of the ball, and realizes a ball having the flight, gripping properties and ball controllability of the hand stitched ball while keeping the quality of the laminated ball (weight, size, sphericity, durability, shape maintenance, and an enhancement in strength for a change with the passage of time).
The present invention provides a ball for a ball game comprising an elastic bladder having the form of a spherical hollow body into which compressed air is charged, a reinforced layer formed on a whole surface of the bladder, and a plurality of leather panels bonded onto the reinforced layer directly or through a cover rubber layer, wherein a peripheral edge portion of the leather panel is folded toward an inside and a thickness adjusting member bonded onto the back of the leather panel surrounded by the folded portion of the leather panel. According to such a structure, a trench having the same shape as the shape of a hand stitched ball is formed on a joint of the adjacent leather panels. The trench reduces air resistance, enhances gripping properties and gives easiness to grip the ball. Accordingly, operability and ball controllability can be enhanced. By the existence of the thickness adjusting member, the back of the leather panel is a flat face. Consequently, the difference in step caused by the folding does not appear on the surface of the leather panel.
A ball for a ball game according to the present invention is characterized in that the peripheral edge portion of the leather panel is folded toward the inside by about 180 degrees. According to such a structure, the folded portion of the leather panel is bonded onto the cover rubber layer or the reinforced layer. Therefore, even if peeling is caused on the panel joint, there is little possibility that the folded portion might be turned over to appear on the surface of the ball.
A ball for a ball game according to the present invention is characterized in that the peripheral edge portion of the leather panel is folded toward the inside by about 90 degrees. According to such a structure, the folded portion of the leather panel is not inserted between the cover rubber layer or the reinforced layer and the thickness adjusting member. Therefore, there is no possibility that the thickness of the folded portion might appear as an irregularity on the surface of the leather panel.
A ball for a ball game according to the present invention is characterized in that the leather panel is bonded in the joint to the adjacent leather panel. According to such a structure, water can be prevented from entering the joint of the leather panels. In addition, the peeling of the leather panel can be prevented so that durability can be enhanced.
A ball for a ball game according to the present invention is characterized in that a notch is formed in the folded portion of the leather panel. According to such a structure, the folding can easily be performed like a curved line.
A ball for a ball game according to the present invention is characterized in that the thickness adjusting member is made of a woven fabric. According to such a structure, the bias effect of the woven fabric can prevent the ball from being deformed when external force is applied to the ball. Also in the case where such external force to damage the leather panel is applied, the force is intercepted by the woven fabric so that the bladder can be protected.
A ball for a ball game according to the present invention is characterized in that the thickness adjusting member is made of a shock absorbing member. According to such a structure, the external force applied to the ball is absorbed and relieved by the shock absorbing member. Consequently, a feeling can become soft when the ball hits a human body.
A ball for a ball game according to the present invention is characterized in that the thickness adjusting member has a lamination structure of the woven fabric and the shock absorbing member. According to such a structure, the shock absorbing member and the bladder which are provided on the inside can be protected by the woven fabric, and the shock absorbing function can be obtained by the shock absorbing member.
A ball for a ball game according to the present invention is characterized in that the shock absorbing member is formed of a foaming member, a nonwoven fabric, a bulky woven fabric or a honeycomb construction member. According to such a structure, the shock absorbing member and the bladder which are provided on the inside can be protected by the woven fabric, and the shock absorbing function can be obtained by the shock absorbing member.
A ball for a ball game according to the present invention is characterized in that the reinforcing member is provided between the leather panel and the thickness adjusting member. According to such a structure, when force to extend the leather panel is applied by the internal pressure of the bladder, the reinforced member inhibits the extension so that the expansion of the ball can be suppressed. Also in the case where the external force to damage the leather panel is applied, the force can be intercepted by the reinforced layer so that the bladder can be protected.
A ball for a ball game according to the present invention is characterized in that the reinforced layer is made of a polyester film, a PVC film, a polyethylene film or a polypropylene film. According to such a structure, it is possible to obtain a reinforced layer having flexibility, light weight and small thickness.